Previous Editions__________________________________________________________________________SSRL Headlines Vol. 10, No. 12 June, 2010__________________________________________________________________________
Contents of this Issue:
A team that included scientists from NASA Ames Research Center, Cornell
University, Xradia Inc., and SSRL has developed a technique that can be used to
image bone structure in 3D at high (30 nanometer) resolution. They used the
transmission X ray microscope (TXM) on SSRL Beam Line 6-2 to visualize bone
from mice that had undergone a process to simulate weightlessness. Using
mathematically reconstructed tomography (nano-CT) images, they created a 3D
image of the bone's nanostructures. The scientists were also able to measure
bone density on a fine scale.
These techniques can be used to discern the difference between normal and
diseased or distressed bone, and responses to treatment. They can also
characterize nanoscale changes in bone structures due to weightlessness, and
identify differences in subsequent bone regrowth upon weight bearing. This
work is of particular interest to NASA because they are interested in the
long-term effects of weightlessness on bone density and nanostructure. This
work was published in the June issue of Microscopy and Microanalysis.
To learn more about this research see the full scientific
highlight
The capsid that surrounds viruses is formed from subunit proteins that interact
in specific ways to form a tight shell. The processes of coming together and
forming interactions are multistep and complex and are fundamental events to
acquire viral infectivity. The capsid maturation process of the Nudaurelia
capensis omega virus includes pH-dependent conformational changes and
auto-proteolysis. Like many human viruses such as HIV and herpes virus, NwV,
an insect virus, requires these specific structural changes to become
infectious.
A group of scientists led by Prof. Jack Johnson of The Scripps Research
Institute performed equilibrium and time-resolved small angle x-ray scattering
(SAXS) using SSRL Beam Line 4-2 to investigate the properties of NwV capsid
maturation. They found that pH-dependent protonation of some of the residues
of the capsid proteins allowed them to pack more closely together causing a
size reduction of the entire provirion. This quick conformational change,
observed in millisecond to second regime, is followed by the slower process of
auto-proteolysis taking place over many hours, resulting in the mature
structure. Interestingly, capsids exposed to a lower pH did not require a
cleavage step to reach the mature structure.
The authors identified three pH-dependent kinetic stages corresponding to
capsid compression and strengthening. Their study expands understanding of
viral maturation processes. This work was published in the April 7 issue of
Biophysical Journal.
To learn more about this research see the full scientific highlight
A team of scientists led by Prof. Dave Stout at The Scripps Research Institute
has used SSRL beam lines to crystallographically screen fragment binding to HIV
protease. They screened 400 fragments and evaluated 800 crystals using SSRL's
high-throughput robotic sample automounter system. They found two novel
surface-binding sites that induce conformational changes in the protease.
Their study shows that applying this high-throughput method can identify new
potential drugs and drug targets that work in combination with existing drug
therapies. This may allow current drugs to continue being effective, despite
viral mutations. This work was published in the March 2010 issue of Chemical
Biology and Drug Design.
To learn more about this research see the full scientific
highlight
SSRL began running in what's called top-off mode last year, with the last few
beam lines approved for top-off earlier this year. Photon beam lines remained
open while electrons were injected into the SPEAR3 storage ring three times a
day to replenish the 200-mA current. Still operating in top-off mode, these
injections now happen once every 10 minutes, or 144 times a day.
"The number one advantage for operating this way is power constancy," said Tom
Rabedeau, who works on beam line development at SSRL. The frequent injections
allow the current to remain relatively stable, dropping only about 1.5 mA
before more electrons are added. Since the optics used to focus and guide the
beams can experience thermal distortion under larger current fluctuations, they
perform better under the nearly constant power load provided by the smaller,
more frequent injections. Read more at:
Catalysts are widely used in many industrial processes, including energy
production and mitigating pollution. New catalysts also hold the key to future
energy technologies such as efficiently splitting water to form hydrogen or
other fuels. To design these technologies, we first need to understand how
catalysts carry out their function on the atomic level. We currently do not
have a unifying predictive strategy (as for example the Standard Model provides
for the field of high energy physics). Jens and his team are leading designers
of new materials, especially for catalysis and energy storage applications,
using advanced techniques of theory, modeling and simulation. Jens' new center
at SLAC will provide a unique capability to understand and model new materials
which can then be synthesized. Our light sources at SLAC (LCLS and SSRL) offer
valuable techniques for characterizing the new materials. These materials can
then be tested for improved catalytic properties with the ultimate goal of
finding real world applications. Read more at:
See also June 4 SLAC Today article at:
Plans are underway for the Annual SSRL/LCLS Users' Meeting and Workshops,
October 17-21, 2010. Mark your calendar and plan to participate to learn about
new developments and exciting user research at LCLS and SSRL. It is also a
great time to interact with other scientists, potential colleagues, and vendors
of light source-related products and services. Check back later for more
details and registration.
Please take a few moments to consider nominating your colleagues or students
for one or more of the following awards which will be presented at the Joint
SSRL and LCLS Users' Meeting, October 17-21, 2010:
"It's a practical, hands-on type of workshop," said co-organizer Mike Toney, a
SLAC scientist with SSRL. "What we explained and demonstrated is typically not
found in textbooks." A working understanding of the beam lines at SSRL is
crucial to successfully studying nano- and atomic-scale structures.
Some of the experimental methods covered include thin-film scattering, powder
diffraction, small angle x-ray scattering and x-ray reflectivity. One and
one-half days of this workshop were devoted to explanatory talks, one day to
gaining hands-on experience at the SSRL beam lines, and the last half day was
spent working on data analysis. See:
Due to the extreme fire danger in Northern California, SLAC policy requires
that anyone who smokes on SLAC property do so in specifically designated areas.
The policy also requires anyone barbecuing on SLAC property to first obtain a
Hot Work Permit. Contact building managers for more information on the
designated smoking areas for specific buildings/areas which should include
fire-proof disposal containers at least 20 feet from readily combustible or
flammable materials. In addition, designated smoking areas need to be at least
20 feet away from any doorway, walkway, air intake or functional window and not
in a pathway that a non-smoker must use to enter a building. Furthermore,
smoking is expressly prohibited along the Linac Roads, in any area near
grasslands, and in SLAC or General Services Administration vehicles. For more
information, see http://today.slac.stanford.edu/feature/2008/smoking-policy.asp
http://today.slac.stanford.edu/feature/2008/smoking-policy.asp
The annual meeting of the National User Facility Organization (NUFO), held June
7-9, 2010, at Brookhaven National Laboratory, focused on a number of issues of
interest to users-among them educational and community outreach approaches,
streamlined access processes for non-US citizens, further standardization of
user agreements, and industrial use of various user facilities. NUFO
represents the interests of users of national user facilities as well as
American users of international user facilities. The next meeting will be held
at SLAC in 2011. Contact Cathy Knotts, Katherine Kantardjieff, or anyone on
the NUFO Steering Committee to suggest discussion topics for the next meeting.
To access copies of the presentations from the 2010 meeting or for further
information about NUFO activities, visit http://www.nufo.org or e-mail info@nufo.org.
__________________________________________________________________________
SSRL Headlines is published electronically monthly to inform SSRL users,
sponsors and other interested people about happenings at SSRL. SSRL is a
national synchrotron user facility operated by Stanford University for the
U.S. Department of Energy Office of Basic Energy
Sciences. Additional support for
the structural biology program is provided by
the DOE
Office of Biological and Environmental Research, the NIH
National Center for Research Resources and the NIH Institute for General Medical
Sciences. Additional information about
SSRL and its operation and schedules is available from the SSRL WWW
site.
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